US65 datasheet(9/12 Pages) MELEXIS

9 / 12 page

US65 / US66

Two-Coil Low Noise Fan Driver

High Output Current

3901090209

Page 9 of 12

Preliminary Datasheet

Rev 006

Jan/07

12 Application Information

Typical computer fan application circuit

13 Application Comments

During fan rotation, the coils may affect the stability of the VDD voltage. To filter eventual spikes, it is

recommended to add a 100nF decoupling capacitor between VDD pin and GND, closer to the chip.

If the FG/RD pull-up resistor is connected to VDD, a diode should be connected between the fan supply

voltage and the common point of the fan coils to avoid parasitic effects on FG/RD output.

The voltage VDD and VPU can be physically the same voltage source. However, the pull-up voltage VPU is

generally connected to a different digital power source at 5V as it feeds the FG or RD signal to an IC

interface.

When the default slope is sufficient, the pin SLOPE may just be left open.

For slope adjustment, it is required to connect a resistor RSLOPE between the SLOPE pin to ground. The value

of the resistor modifies the output slope as shown in the performance graph.

US65 Datasheet(PDF) 9 Page - Melexis Microelectronic Systems